Heat capacity measurements under magnetic fields are carried out on one-dimensional Heisenberg antiferromagnets, a spin-Peierls (SP) and Haldane gap system. In the SP system CuGeO3, the jump in the heat capacity corresponding to SP transition is observed under fields up to 13 T. The obtained field-temperature phase diagram is in good agreement with the previous results of magnetic measurements. The heat capacity follows the exponential temperature dependence at low temperatures under zero field, while it approaches T3-dependence under external field. The heat capacity of Haldane gap system NINO is almost the same as that of NENP. The energy gap at and above Hc is caused by the existence of the transverse moment.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering